Composite elastomeric flexible elements are commonly used between load-bearing structural members in order to accommodate motion between the structural members while significantly reducing mechanical fatigue of the structural members and providing some resistance to the motion. For example, composite elastomeric flexible elements are used for supporting structural members of buildings, bridges, and floating offshore drilling and production facilities, in order to accommodate motion due to a variety of sources. These sources range from frequent recurring events to infrequent extreme events. For example, a building or bridge may accommodate recurring thermal expansion and contraction due to daily and seasonal variation in temperature, as well as infrequent extreme events such as wind loading due to violent storms and seismic shock due to earthquakes. Floating offshore drilling and production facilities may accommodate recurring wave and tidal motion, as well as infrequent extreme events such as violent storms and collisions with other vessels.
Recently there has been a desire to monitor the health of structural members in order to maintain structural integrity while controlling maintenance costs by more intelligent scheduling of repair and replacement of the structural members. For example, there has been an increased public awareness of aging infrastructure due to news reports of collapsing bridges and leaking pipelines. There has been a corresponding interest among several oil companies in “asset integrity management” of their infrastructure. Integrity management encompasses a broad scope of threats, from corrosion and stress fatigue, to “third party” damage such as sabotage. The focus has been on the stresses and strains developed in metal parts, and such methods have involved visual inspections as well as mechanical and electromechanical solutions.